Nóirín O'Sullivan was doomed from day one.She was supposed to be a mould-breaker who could change the image of a downtrodden, under-resourced, scandal-ridden force.

On the day she was appointed in November 2014, the mother of three set a target of working hard to "strengthen the trust and confidence in the service".

More than two years on, it's clear that she will not be able to achieve this.

The evidence suggests Ms O'Sullivan brought an unmanageable amount of baggage with her when she became the first woman to lead An Garda Síochána.

The aesthetically close connection to her predecessor Martin Callinan was a bad starting point - even if the pair were miles apart on a personal level.

Since then her reign has been dogged by whistleblowers, the upsurge in gangland activity, the strike threat, inaccurate crime statistics, a trip to San Diego and even her use of Gmail.

The Government has known for some time that Ms O'Sullivan is a liability but after the Callinan experience, the Taoiseach and Justice Minister know losing a second commissioner could have destructive consequences.

Last May, reports emerged that legal council for Ms O'Sullivan had alleged malice in the motivation of Garda whistleblower Sgt Maurice McCabe to the O'Higgins inquiry.

Clare Daly told Frances Fitzgerald it was "obvious" the commissioner had to go. "Unless you act, she's going to take you with her," Ms Daly said in a way that made minds drift back to Alan Shatter's resignation as minister.

"Only Fianna Fáil saved her at that stage," said a garda source familiar with the fallout. Just like on this occasion, Micheál Martin didn't join the clamour calling for a head.

Sources say there has been an acute awareness in Garda HQ that any little thing could bankrupt the commissioner's authority to the point of no return. The drip, drip of negative stories, including some fake news such as the alleged promotion of her non-existent bridesmaid, has had a cumulative effect.

Brendan Howlin's intervention yesterday raised eyebrows among journalists who have covered the Garda scandals. The unfounded rumours alluded to by Mr Howlin have been in circulation for a number of years.

Ms O'Sullivan last night insisted she had "no knowledge of the matters referred to by Deputy Howlin".

Taoiseach Enda Kenny made the point that Ms O'Sullivan "vehemently denies" claims that she was aware of a campaign against Sgt Maurice McCabe.

It will take until at least November for Supreme Court Judge Peter Charleton to get to the facts - but there is no happy ending here. He must effectively decide whether Ms O'Sullivan is victim or perpetrator.

If the Government allows the commissioner to remain in place and then any wrongdoing on her part, no matter how minor, does emerge, the resignations will stretch from the Phoenix Park to Merrion Street.

But even if the judge says the commissioner is the one who has been unfairly targeted, the damage inflicted by this furore may be too much to withstand.

When the calls for her head peaked last May, the Taoiseach was on a trip to Washington where he chose to publicly back the commissioner.

Today Mr Kenny is in Poland on the latest leg of his Brexiteering. It will be interesting to see if after the intervening nine months of controversy, he still maintains the same confidence.